The solo leveling limit conjecture

Interesting calculations, but I do have to disagree with one point: AoEs can actually be far more efficient DPE than single target attacks if you hit enough targets. In general, if you hit 3+ enemies with a cone or 4+ enemies with a targeted AoE you'll do more efficient damage than single target blasts.

In addition, some characters (in particular Blasters and Masterminds) can regain endurance faster than they can burn it without needing any extreme measures in slotting or power selection. My Archery / Energy Blaster cannot run out of endurance unless he gets sapped or hit with a recovery debuff... his most energy-intensive attack chain plus his toggles do not equal his recovery, and that's with no recovery uniques or procs and a sub-100 million build. A fully frankenslotted character or one using cheap to mid-price set IOs can easily have 50-60% or more endurance reduction in every power, so if you don't use a lot of toggles you can often get your recovery higher than your endurance use with just stamina and a few minor set bonuses (or even just Stamina). My Bots/Traps MM doesn't even have Stamina (or any recovery IOs) and he only ever needs blue pills in AV fights where he has to spam Web Grenade... in normal combat he uses less endurance per fight than he regains since the bots do 90% of the work (I tend to stand there with the Leadership toggles on immobilizing any bosses and tossing an occasional heal or Acid Mortar).

Of course, with the exception of Masterminds most ATs that can fight +2 bosses at lower levels are pretty toggle-heavy so your math still holds up well in practice... truly endurance neutral Brutes or Scrappers tend to require either a massive investment or a sub-optimal attack chain / toggle use. And Masterminds are quite slow to level until the 20s compared to Brutes and Scrappers so I'm not sure if their endurance advantage makes up for that.

Still, if you had IOs pre-crafted in storage (so no lost time marketing for them) I'd think something like a Thugs/Traps MM or Fire/Regen Scrapper could beat your numbers. The key would be fully slotting IOs in the mid 20s to maximize survivability and damage, since endurance is pretty much a non-issue for those power sets.

Concerning practical play:

The only way I could approach 36 hours to 50 (or, more accurately, have approached, which also discards exploits) was on a double XP weekend where I was on an 8-man team almost constantly during my play. I did go 1-50 during the double XP period, though I never took a more accurate measure of my time (and, obviously, I did in fact sleep)

Only things that end up coming to mind are things that can slow you down - calculations aside, you're going to run into groups that give more or less XP, arcs that do, etc. I'd assume, however (and I know what that ends up doing...) that it all balances out... if I ran your challenge, in other words, I might break the time (say) at 25, then hit some particularly nasty group (resistances, lower XP, widely spread missions - how's travel time in this anyway? Run mission, log, log in, use mission teleporter?) I can't avoid that drags me back into range by 30.

See my Guides and Tutorials

If I was going to try this challenge, and I found some way I could temporarily beat the time, I'd ouro that thing to death.

EDIT:
Just ran a sample mission or two on a L36 blaster.
First (PWNZ badge, heroic) I got 43K XP of which 8800 was mission completion bonus. That was in patrol mode, so "raw" numbers are 2/3 of those.
Second (radio mission, heroic, defeat boss only) I got 18K of which 6400 was mission completion bonus. Still patrol mode. From the time I clicked "enter mission" to the time I clicked "Exit" was 2 min 19 seconds. 854K for level, so we have on the order of 1% of level XP per mission complete bonus, at 2 minutes per mission, at level 36. So again it looks like we're not going to get more than a couple percent of speedup for mission completions.

So I can't see any reason why we'd want to do this anywhere but AE.

I got my claws/sr brute from 30 to 50 in about 6 hours and my fire/shield scrapper from 20 to 50 in about 8 all over the last week.

solo?

Power Sink on an /elec blaster after it becomes available would seem to also throw the endurance calculations out of whack.

OK, it's apparent you aren't going to share details, but are you doing something we could consider remotely normal? Are you doing something like fighting foes that give huge reward compared to how easy they are to kill? (Bearing in mind that this is all sort of slippery, since even the metric of fighting +2 bosses in a never ending stream would probably be considering that we're not allowed to do that, and not at full reward when we could even approximate it.)

Brainz is da sexeh!

I tried to run an optimized solo streak to 50 on my elec/sd scrapper last week. I made a custom AE mish for the purpose, built to fit the strengths of the toon. I made it to 50 in 82 hours, and that's nowhere near the 36 hrs.

I didn't know about this thread back when I decided to roll and challenge myself this way, hence the reason I went with AoE heavy approach.

The reason for picking AoE was also based on 3 things: More kills in one shot = faster xp, and more kills/sec = more inspiration which in turn leads to alleviating the problem of endurance and survival. The third reason was the removal of travel between missions/contact which I figured should compensate for the lack of end bonus. An unexpected added bonus I found was that levelling on a high level mish didn't lower my xp/min as I was still auto-sk'd to min level of the mish.

I found 2 issues slowing me down: Survivability and endurance. For the ride up to SO's, hitting and killing stuff with ST was fairly slow, so I found an AE mish with nothing but high rewarding, single mob spawns. Needless to say, they took me down often enough for it to be tedious at best and with the sparingly few insp slots it was less than fun.

Once getting past 32 things really started to pick up, and with the second big AoE and more insp slots, I could stay at defense cap with purple insps and still get enough insps to keep my end lasting reasonably well, even though I sometimes ended up nearly detoggling on the last boss of the spawn, thus having to rest before next bunch.

Basically, I don't see it happening to even reach <50 hours. Especially if you'd try to survive with the drops from single enemies.

Does this conjecture take influence into consideration? There is a significant difference when truely SOLOING.

Based on the numbers provided, it seems that you are assuming an optimized build through-out the experience of lvl2-50. So based on mathematical rigour, I'm going to step-down because it seems that this is more of a regression analysis to find a theoretical limit (which is fine - I just can't do it well enough to give any meaningful insight).

Practically, I did try. Using fire/regen, and not using sands of mu (no, AoE right? That really hurts ), I stayed ahead until DO's would have helped. The lack of ideal acc and end drain with attacking hurt most.

Edit: general survivability isnt as good either, but that maybe a secondary issue

I'll try again when I have time with a toon that will start with 5million inf to better simulate your model, but as it stands many factors are contributing to a less-than-ideal leveling experience.

I feel that this will become, as it stands, a mathematically speculative exercise. I really wish I had the skills to contribute further.

Woops... miss read. Thought one of the solo requirements was "no AoE," and I'm wrong. Oh, well. I'll try again with *all* the correct data now.

Thanks for a prompt reply.